<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let score = +prompt('请输入你的分数')
        if(score >= 90){
            alert('A')
        }else if(score >= 80 && score < 90){
            alert('B')
        }else if(score >= 70 && score < 80){
            alert('C')
        }else if(score >= 60 && score < 70){
            alert('D')
        }else{
            alert('E')
        }
    </script>
</body>
</html>